Mixed organometallic compositions including at least three metals, and uses thereof as fuel additives

ABSTRACT

Compositions including at least three metals (M1, M2, M3) are disclosed. The first metal (M1) is at least one metal selected from the iron group or the manganese group, and is preferably selected from iron, manganese, cobalt and nickel. The second metal (M2) is at least one metal selected from the rare earth group and is preferably selected from cerium, lanthanum, neodymium and praseodymiium. The third metal (M3) is selected from the group of alkaline or alkaline-earth metals, and is preferably selected from barium, strontium, calcium and lithium. The weight ratio (R) of metal (M3) to metal (M2) is greater than 0.15, and preferably greater than 1.5.

This application is a 371 of PCT/FR/97/01369, Jul. 23, 1997.

This invention relates to mixed organometallic compositions, containingat least three metals belonging respectively to the manganese or irongroup, the rare earth group, and the alkaline or alkaline earth group.It also relates to applications of these organometallic compositions asfuel additives for hydrocarbonic liquid fuels or motor fuels, such asfuel oil and diesel fuel.

We are already aware of the use of organic acid organometallic ororgano-metalloid complex salts as combustion additives to hydrocarbonicliquid fuels, for example, to ease and improve the combustion of thesefuels. Such additives are, for example, composed of a complex saltobtained from an organic acid (fatty acids with more than 7 carbonatoms) and iron (see FR-A-2 172 797), or manganese (see FR-A-2 486 083),or rare earth metals, in particular cerium (see FR-A-2 359 192). Theapplicants have also proposed mixed combustion additives containing ironand cerium (see EP-A-1 12 219).

The mechanism of action of these additives on the combustion, inparticular, of a fuel oil seems relatively well known: the metallicoxides contained in the additive would adsorb on the asphaltenes alwayspresent in a fuel oil and, because of their catalytic effect on thecombustion of these asphaltenes, these metallic oxides would thus reducethe quantity of solid unburned components released during thecombustion.

However, because of the actual rarity of the components, the use ofcompounds with a rare earth base is costly. Therefore, to reduce thecost, many substitute organometallic compounds have also been researchedand tested by the applicants, without much success.

Nevertheless, surprisingly so, it was found that not only can thecontent in rare earths be considerably reduced by the adjunction of athird metal of the alkaline and or alkaline earth type, but also, thequality of these additives is considerably improved.

The applicants have thus established that, surprisingly so, theadjunction of a third element along side the iron and cerium allows, notonly to improve on the qualities of combustion as far as the environmentis concerned, in particular in an urban area--as these combustionqualities are subject to regulations that are more and more strict--butalso to reduce the cost of the additive.

The purpose of this invention is therefore to propose mixedorganometallic compositions that contain at least three metals, whoseefficiency as a combustion adjuvant is at least the same as the rareearth and iron salts mixtures with an identical overall metal content,and whose cost, due to the reduction of the rare earth content, issignificantly reduced in relation to these same salts.

The object of this invention is therefore mixed organometalliccompositions, characterized by the fact that they contain organic acidsalts of at least three metals M1, M2 and M3,

the first metal, M1, being composed of at least one metal belongingeither to the iron group or the manganese group, preferably a metalchosen from among iron, manganese or nickel,

the second metal, M2, being composed of al least one metal belonging tothe rare earth group, preferably a metal chosen from among cerium,lanthanum, neodymium or praseodymium,

the third metal, M3, being chosen from among the alkaline or alkalineearth metal group, preferably, a metal chosen from among barium,strontium, calcium or lithium, and by the fact that the R ratio of themass contents of the M3/M2 metals, is greater than 0.15, preferablygreater than 1.5.

Indeed, it has been proved that the addition of a third element to thecomposition, belonging to the alkaline or alkaline earth metal group,makes it possible to unexpectedly reduce, on the one hand, theadditive's content of rare earth, and on the other hand, the level ofthe quantity of solid unburned components produced during the combustionof a fuel oil containing said composition as an additive. Furthermore,for an identical overall metal content in the composition, the use ofcalcium in this composition makes it possible to reduce by such amountthe quantity or rare earth necessary and therefore to reduce the cost ofthe additive.

In the description of the object of the invention, and for the remainderof this description, for the M1 metal chosen from among the iron ormanganese groups, iron, because of its low cost, is the preferredelement. It can be used alone or mixed with manganese, cobalt or nickel.

In the same manner, the M2 metal chosen from among the rare earth metalsis preferably cerium. It can be used either alone or mixed withlanthanum, neodymium or praseodymium.

The preferred element for the M3 metal belonging to the alkaline oralkaline earth group is calcium, which can be used either alone or mixedwith lithium, strontium or barium.

The organometallic derivatives of the iron or the manganese group andthe rare earth group can be prepared according to the methods describedin the prior art, in particular in the European patent EP-B-112 219,filed in the name of the applicants, thus making it possible to obtainsolutions highly concentrated in metal and greatly exceeding the normalstoichiometric values.

The solution containing the calcium can be obtained from a hydro-solublesalt, an oxide or a hydroxide and a fatty acid containing, preferably,more than 7 carbon atoms. Other organic acids can also be used such as,for example, alkyl-, aryl- or alkylarylsulfonic acids and carboxylicacids with an alkylaryl chain containing, preferably, more than 8 carbonatoms.

The final composition can then be obtained by mixing the solutions, inparticular the iron, cerium and calcium solutions, in an organicsolvent, preferably of the aromatic type, and whose content in aromaticcompounds is greater than 50% and preferably greater than 80%. Theproduct obtained is stable and fluid at room temperature, which allowsfor great ease of implementation.

Preferably, the compositions as set forth in the invention contain acontent in M1 metal of the iron or manganese groups greater than orequal to 30% by weight, in relation to the total weight of the metals,and a content in M2 rare earth metal greater than or equal to 10% byweight. The content in M3 metal belonging to the alkaline or alkalineearth group is directly tied to the content in M2 rare earth metal bythe ratio R of mass contents of the M3 and M2 metals which must begreater than 0.15 and, preferably, greater than 1.5.

These compositions are soluble in hydrocarbons and therefore can beadded in adequate percentages to the hydrocarbonic liquid fuels andmotor fuels such as heavy, light or domestic residual fuel oils, and gasoils, in such a way that said fuels or motor fuels contain between 10and 100 ppm of added metals, and preferably, between 40 and 100 ppm.

The use of such an additive, with the contents as indicated above, in afuel makes it possible to reduce the emission of solid unburnedcomponents and therefore to respect the regulations in force. It alsoauthorizes the operation of the heating plant with less excess air thanin the traditional conditions; thus the trimetallic additive allows forthe indirect reduction of the emission of nitrogen oxides.

The performance of the combustion plants is also improved by:

an operation with less excess air,

a reduction of the loss in smoke of solid unburned components,

less clogging of the exchange surfaces.

Lastly, the operating cost will be minimized by a greater mean timebetween sweepings, cleanings and in particular, disposals on land ofsoot, collected for example, on the dust collectors.

The following example is intended to illustrate the invention in a nonrestrictive manner.

BRIEF DESCRIPTION OF DRAWINGS

In this example, we will refer to the attached drawings, of which FIGS.1 and 2 are graphs that illustrating the results of tests completed inthe conditions that will be described in this example.

EXAMPLE

We successively feed a boiler with the same liquid fuel, without anyadditives for the first test (test A), then with the addition of acomposition containing at least two metals (iron and cerium) asdescribed in the patent EP-B-112 219 filed in the names of theapplicants (test B), and lastly containing the trimetallic additive thatis the object of this invention (test C).

The injection of the additives in the liquid fuel is carried out using ametering pump at the level of the heating device. The quantities ofadditive introduced in the fuel are such that the total content in metaladded to the fuel by said additives is of 40 ppm (expressed in relationto the total weight of the fuel and the additive).

Each test is carried out at three levels of excess air that vary byapproximately 3% to approximately 1.5% of oxygen in the smoke.

The boiler is a smoke-water tube type boiler, with the followingcharacteristics:

furnace power: 7000 th/h,

furnace diameter: 1200 mm,

furnace length: 4920 mm,

burner: nominal fuel flow of 550 Kg/h with an angle of diffusion of 70°C. and an atomization realized by compressed air at 6.10⁵ Pa (6 bars).

The liquid fuel used for each test is a heavy fuel oil, whose mainphysicochemical characteristics are presented in Table 1. In this table,all percentages are expressed in mass.

                  TABLE 1                                                         ______________________________________                                        Characteristics of the fuel oil                                                             STANDARDS/                                                      CHARACTERISTICS                                                                             METHODS      UNITS   RESULTS                                    ______________________________________                                        Density at 15° C.                                                                    NF T 60-172  Kg/m.sup.3                                                                            1018.4                                                   ASTM D4052                                                      Viscosity at 50° C.                                                                  NF T 60-100  mm.sup.2 /s                                                                           527.88                                                   ASTM D445                                                       Viscosity at 100° C.                                                                 NF T 60-100  mm.sup.2 /s                                                                           39.09                                                    ASTM D445                                                       Carbon                     %       84.45                                      Kjeldahl nitrogen                                                                           ASTM D3228   %       0.44                                       Hydrogen                   %       9.81                                       Sulfur                     %       2.72                                       Measured HHV               MJ/kg   41.84                                      Calculated LHV             MJ/kg   39.76                                      Asphaltenes   NFT60-115    %       7.6                                                      IP 143                                                          Conradson carbon residue                                                                    ASTM D4530   %       14.4                                       Ashes         NF M 07-045  %       0.039                                                    IN ISO 6245                                                     Insolubles    NF M 07-063  Ppm     250                                        Total metals  Atomic emission                                                                            Ppm     240                                        ______________________________________                                    

The process conditions are very much identical for all three tests andare grouped together in Table 2.

                                      TABLE 2                                     __________________________________________________________________________    Process conditions                                                                         Test A   Test B   Test C                                         CHARACTERISTICS                                                                            (without (+ bimetallic                                                                          (+ trimetallic                                 Total concentration in metals                                                              additive)                                                                              additive)                                                                              additive)                                      brought by the additives                                                                   0        40       40                                             (in ppm in relation to the fuel)                                                           A1 A2 A3 B1 B2 B3 C1 C2 C3                                       __________________________________________________________________________    Total oxygen (%)                                                                           3.1                                                                              2.2                                                                              1.4                                                                              3.4                                                                              2.4                                                                              1.7                                                                              3.0                                                                              2.1                                                                              1.4                                      Fuel oil flow (kg/h)                                                                       516                                                                              515                                                                              514                                                                              504                                                                              516                                                                              510                                                                              515                                                                              510                                                                              512                                      Fuel oil pressure                                                                          8.0                                                                              7.9                                                                              8.0                                                                              7.8                                                                              7.8                                                                              7.8                                                                              7.8                                                                              7.7                                                                              7.9                                      (10.sup.5 Pa)                                                                 Fuel oil temp. (° C.)                                                               74 74 75 75 74 75 75 75 75                                       Fuel oil viscosity (mm.sup.2 /s)                                                           125                                                                              120                                                                              120                                                                              120                                                                              125                                                                              120                                                                              120                                                                              120                                                                              120                                      Pulv. Air. Pressure                                                                        6.2                                                                              6.2                                                                              6.0                                                                              6.0                                                                              5.9                                                                              6.1                                                                              6.1                                                                              6  6.1                                      (10.sup.5 Pa)                                                                 Pulv. Air. Temp. (° C.)                                                             23 23 23 25 25 25 23 24 24                                       __________________________________________________________________________

For each test and for each of the three combustion excess air values, wecomplete an isokinetic sampling and a weight determination of the solidunburned components produced during the combustion, as well as analysesof the combustion gases. For measurement needs, the unburned componentsare drawn at the chimney in a steady flow area, at a height ofapproximately 5 meters.

These measurements or analyses are completed at least one hour after thebeginning of the injection of each of the two additives, the boilerbeing fed for at least one hour with the fuel containing no additivesbetween each of the tests.

The results of the measurements and analyses will be provided in Table3.

                                      TABLE 3                                     __________________________________________________________________________    Measurements of the unburned components and analyses of the combustion        gases                                                                                      Test A   Test B   Test C                                         Total concentration in metals                                                              (without (+ bimetallic                                                                          (+ trimetallic                                 Brought by the additives                                                                   additives)                                                                             additive)                                                                              additive)                                      (in ppm in relation to the                                                                 0        40       40                                             fuel)        A1 A2 A3 B1 B2 B3 C1 C2 C3                                       __________________________________________________________________________    Total oxygen (%)                                                                           3.2                                                                              2.2                                                                              1.4                                                                              3.5                                                                              2.5                                                                              1.7                                                                              3.0                                                                              2.1                                                                              1.4                                      Solid unburned components                                                                  129                                                                              234                                                                              348                                                                              88 144                                                                              247                                                                              90 152                                                                              245                                      (mg/Nm3 at 3% of O.sub.2)                                                     Calculated CO.sub.2 (%)                                                                    13.3                                                                             14.1                                                                             14.7                                                                             13.2                                                                             13.9                                                                             14.5                                                                             13.5                                                                             14.1                                                                             14.8                                     CO (ppm)     3  5  13 2  -- -- 0  0  7                                        NOX (ppm)    352                                                                              333                                                                              314                                                                              342                                                                              335                                                                              313                                                                              345                                                                              325                                                                              313                                      NOX (mg/Nm3  746                                                                              658                                                                              600                                                                              750                                                                              674                                                                              603                                                                              719                                                                              653                                                                              593                                      at 3% of O.sub.2                                                              __________________________________________________________________________

FIG. 1 of the attached illustrations represents in a graphical mannerthe variations of the quantities of solid unburned components (mg/Nm³ at3% of O₂) during each of the three tests, in relation to the content incombustion oxygen (%).

In the same way, FIG. 2 is a graphical representation of the variationsof nitrogen oxides (mg/Nm³ at 3% of O₂) measured, in relation to theunburned products during the combustion.

In FIG. 1, we can see that for a constant oxygen content, the presenceof an additive in the combustion fuel oil makes it possible toappreciably reduce the quantities of unburned components during saidcombustion.

The trimetallic additive (test C) that is the object of this invention,present in a fuel gas with a content of 40 ppm, allows:

to reduce the quantity of solid unburned components by approximately 30%to approximately 35% compared with a same fuel gas without the additive(test A), when the oxygen content of the smoke varies appreciably from1.5% to 3.0%. This reduction in unburned components is of approximately20% for the bimetallic additive (test B).

to improve by approximately 50% the performances obtained with thebimetallic additive whose composition is described in EP-B-112 219.

Furthermore, in FIG. 1, we note that for a same target of quantity ofsolid unburned components, the presence of the trimetallic additiveallows for the boiler to operate with less excess air.

The quantity of nitrogen oxides produced during a combustion beingproportional to the excess air of said combustion, the trimetallicadditive that is the object of this invention allows for the indirectreduction of the quantities of nitrogen oxides produced during thecombustion of a fuel oil to which the composition that is the object ofthis invention has been added.

FIG. 2 illustrates that for a same content of solid unburned components,the use of the trimetallic additive (test C) allows for the reduction ofthe emission of nitrogen oxides by approximately 10% when compared withthe combustion of a same fuel gas without the additive.

Furthermore, the trimetallic additive makes it possible to limit theemission of unburned components to very low values (between 50 and 100mg/Nm³ at 3% of O₂) without the costly and constraining recourse tocomplicated dust collectors.

The use of the trimetallic additive that is the object of this inventionmakes it possible to attain a better compromise between the emissions ofthe solid unburned components and those of the nitrogen oxides.

The performance of the combustion plants can therefore be improved by:

a reduction of the excess air, therefore of the nitrogen oxides producedduring said combustion,

a reduction of the losses in smoke by reduction of the solid unburnedcomponents,

a reduction of the clogging of the exchange surfaces.

Furthermore, the operating cost can also be reduced due to fewersweepings, cleanings and disposals on land of soot caught for example inthe dust collectors.

What is claimed is:
 1. A mixed organometallic composition comprisingorganic acid salts of at least three metals M1, M2 and M3, whereinM1 isselected from the group consisting of at least one metal belonging toeither the iron group or the manganese group, M2 is selected from thegroup consisting of at least one metal belonging to the rare earth metalgroup, M3 is selected from the group consisting of at least one metalbelonging to the alkaline or the alkaline earth group, and wherein the Rratio of the mass contents of metals M3/M2, is greater than 0.15.
 2. Thecomposition as set forth in claim 1, wherein said M2 is a metal selectedfrom the group consisting of cerium, lanthanum, neodymium andpraseodymium.
 3. The composition as set forth in claim 1, wherein saidM3 is a metal selected from the group consisting of barium, strontium,calcium and lithium.
 4. The composition as set forth in claim 1, whereinsaid composition comprises, in relation to the total weight of themetals, at least 30% by weight of the M1 metal and at least 10% byweight of the M2 metal.
 5. The composition as set forth in claim 1,wherein the organic acid is selected from the group consisting of fattyacids that have more than 7 carbon atoms.
 6. The composition as setforth in claim 5, wherein the organic acid salts arc salts of alkyl,aryl, or alkylaryl sulfonic acids or carboxylic acids with an alkylarylchain containing more than 8 carbon atoms.
 7. The composition as setforth in claim 1, wherein said organic acid salts are diluted in anorganic solvent.
 8. The composition as set forth in claim 1, whereinsaid M1 is a metal selected from the group consisting of iron,manganese, cobalt and nickel.
 9. The composition as set forth in claim 8wherein the M1 element is iron.
 10. The composition as set forth inclaim 2, wherein the M2 element is cerium.
 11. The composition as setforth in claim 3, wherein the M3 element is calcium.
 12. The compositionas set forth in claim 1, wherein the R ratio of the mass contents ofmetals M3/M2, is greater than 1.5.
 13. The composition as set forth inclaim 7, wherein the organic solvent is of the aromatic type.
 14. Thecomposition as set forth in claim 13 wherein the organic solventcomprises aromatic molecules in an amount greater than 50% by weight.15. The composition as set forth in claim 14, wherein the organicsolvent comprises aromatic molecules in an amount greater than 80% byweight.
 16. A hydrocarbon fuel or motor fuel comprising as an additive amixed organometallic composition comprising organic acid salts of atleast three metals M1, M2 and M3, whereinM1 is selected from the groupconsisting of at least one metal belonging to either the iron group orthe manganese group, M2 is selected from the group consisting of atleast one metal belonging to the rare earth metal group, M3 is selectedfrom the group consisting of at least one metal belonging to thealkaline or the alkaline earth group, and wherein the R ratio of themass contents of metals M3/M2, is greater than 0.15.
 17. The hydrocarbonfuel or motor fuel as set forth in claim 16, wherein said fuel comprisesgreater than 10 ppm of said additive composition, based on the totalconcentration in added metals of the additive composition.
 18. Thehydrocarbon fuel or motor fuel as set forth in claim 17, wherein saidfuel comprises greater than 40 ppm of said additive composition, basedon the total concentration in added metals of the additive composition.19. The hydrocarbon fuel or motor fuel as set forth in claim 16, whereinsaid M1 is a metal selected from the group consisting of iron,manganese, cobalt and nickel.
 20. The hydrocarbon fuel or motor fuel asset forth in claim 19, wherein said M1 is iron.
 21. The hydrocarbon fuelor motor fuel as set forth in claim 16, wherein said M2 is a metalselected from the group consisting of cerium, lanthanum, neodymium andpraseodymium.
 22. The hydrocarbon fuel or motor fuel as set forth inclaim 21, wherein said M2 is cerium.
 23. The hydrocarbon fuel or motorfuel as set forth in claim 16, wherein said M3 is a metal selected fromthe group consisting of barium, strontium, calcium and lithium.
 24. Thehydrocarbon fuel or motor fuel as set forth in claim 23, wherein said M3is calcium.
 25. The hydrocarbon fuel or motor fuel as set forth in claim16, wherein the R ratio of the mass contents of metals M3/M2, is greaterthan 1.5.
 26. The hydrocarbon fuel or motor fuel as set forth in claim16, wherein said composition comprises, in relation to the total weightof the metals, at least 30% by weight of the M1 metal and at least 10%by weight of the M2 metal.
 27. The hydrocarbon fuel or motor fuel as setforth in claim 16, wherein the organic acid is selected from the groupconsisting of fatty acids that have more than 7 carbon atoms.
 28. Thehydrocarbon fuel or motor fuel as set forth in claim 27, wherein theorganic acid salts are salts of alkyl, aryl, or alkylaryl sulfonic acidsor carboxylic acids with an alkylaryl chain containing more than 8carbon atoms.
 29. The hydrocarbon fuel or motor fuel as set forth inclaim 16, wherein said organic acid salts are diluted in an organicsolvent.
 30. The hydrocarbon fuel or motor fuel as set forth in claim29, wherein the organic solvent is of the aromatic type.
 31. Thehydrocarbon fuel or motor fuel as set forth in claim 30, wherein theorganic solvent comprises aromatic molecules in an amount greater than50% by weight.
 32. The hydrocarbon fuel or motor fuel as set forth inclaim 31, wherein the organic solvent comprises aromatic molecules in anamount greater than 80% by weight.